From OpenPCD

As a Mesh Network we describe a network where not only clients (Tags) speak with Servers (Base Stations), but where every node in the network (i.e. every Tag) acts in a dual role. Tags become nodes in a densely meshed network, relaying packets from/to other nodes. Given a high population of tags, it would be possible to extend the actual (relayed) range of a base station way beyond it's direct range.